diff --git a/grudge/symbolic/compiler.py b/grudge/symbolic/compiler.py
index 3aac28bb3c3a8f74d6db255863c811314d464d36..e425fa496411304b88cf305bc13364a1bc95e221 100644
--- a/grudge/symbolic/compiler.py
+++ b/grudge/symbolic/compiler.py
@@ -1018,7 +1018,7 @@ class ToLoopyInstructionMapper(object):
                     lp.Assignment(
                         expr_mapper(var(name)),
                         expr_mapper(expr),
-                        temp_var_type=lp.auto if dnr else None,
+                        temp_var_type=lp.Optional(None) if dnr else lp.Optional(),
                         no_sync_with=frozenset([
                             ("*", "any"),
                             ]),
diff --git a/grudge/symbolic/primitives.py b/grudge/symbolic/primitives.py
index 63adf3dbf7bfa776f35a0691e63967488515fb00..0b9fac20332e505b038ee2ed9bda94485048d8d2 100644
--- a/grudge/symbolic/primitives.py
+++ b/grudge/symbolic/primitives.py
@@ -40,9 +40,9 @@ from pytools.obj_array import join_fields, make_obj_array  # noqa
 
 
 class ExpressionBase(pymbolic.primitives.Expression):
-    def stringifier(self):
+    def make_stringifier(self, originating_stringifier=None):
         from grudge.symbolic.mappers import StringifyMapper
-        return StringifyMapper
+        return StringifyMapper()
 
 
 def _sym():
@@ -658,6 +658,10 @@ class TracePair:
                 self.exterior[index],
                 self.interior[index])
 
+    def __len__(self):
+        assert len(self.exterior) == len(self.interior)
+        return len(self.exterior)
+
     @property
     def int(self):
         return self.interior